A system-in-a-package (SiP) is a number of integrated circuits enclosed in a single package. The SiP performs all or most of the functions of electronic systems, and is typically implemented inside mobile devices such as mobile phones, mobile digital music players, etc. To create a SiP, semiconductor dies or chips containing integrated circuits are typically stacked vertically on a substrate. The integrated circuits are internally connected by fine wires that are bonded to the package. Alternatively, with a flip chip technology, solder bumps are used to join stacked chips together.
Chip-On-Wafer-On-Substrate (CoWoS) advanced packaging technology integrates logic computing and memory chips in a three-dimensional (3D) architecture for advanced products targeting cloud computing, data center, and super computer applications. CoWoS 3-D integration facilitates power-efficient high speed computing while reducing heat emissions.
A diplexer is a passive device that implements frequency-domain multiplexing. Two ports (e.g., L and H) are multiplexed onto a third port (e.g., S). The signals on ports L and H occupy disjoint frequency bands. As a result, the signals on L and H can coexist on port S without interfering with each other. Typically, the signal on port L will occupy a single low frequency band and the signal on port H will occupy a higher frequency band. In that situation, the diplexer consists of a low pass filter connecting ports L and S and a high pass filter connecting ports H and S. Ideally, all the low band signal power on port L is transferred to the S port and vice versa. All the high band signal power on port H is transferred to port S and vice versa. Ideally, the separation of the signals is complete. None of the low band signal is transferred from the L port to the H port. In practice, some power is lost, and some signal power from one port can leak to the other port.